The Jury Is Still Out on Whether Brown Fat Can Make You Thin

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Obesity is a major health problem that carries enormous costs to both the individual and society. Being overweight may limit quality of life and work productivity and cause disease, including type 2 diabetes, heart disease, stroke and some types of cancer. It may even lead to premature death. Obesity is defined as the excess accumulation of fat in the body. This extra fat is a specialized tissue called white fat.

White fat’s job is to store energy to use later. In contrast, brown fat doesn’t store energy; it burns it. Previously, scientists thought only newborn mammals have brown fat, which is believed to help maintain body temperature. However, scientists have recently discovered that adults also have brown fat. This discovery has created a great deal of interest in the scientific community. Researchers want to find a way to increase the amount of brown fat adults have and to turn white fat into brown.

Aaron Cypess, MD, PhD, from the National Institutes of Health, gave a talk about brown fat at Experimental Biology 2019 earlier this month in Orlando, Fla. He looked at how the drug mirabegron—typically used to treat an overactive bladder—activates brown fat. Earlier research found that just one dose of mirabegron caused brown fat to increase blood sugar storage and metabolism. An increase in metabolism can help some people burn more calories, causing them to lose weight. Cypress found that long-term treatment with a lower dose of mirabegron wasn’t able to activate brown fat or increase metabolism significantly. It did, however, provide metabolic benefits—such as better control of blood sugar and insulin levels— that are similar to what happens during moderate exercise. Previous research has found that mirabegron doses higher than those used in this study are not recommended because it may cause damage to the heart, liver or gallbladder.

Researchers will keep working to find a different medication that can increase the energy-burning action of brown fat. This is just one of the many areas of research scientists are working on to better understand and fight the dangers of obesity.


Sandy Martin, PhD, is a professor in the department of Cell and Developmental Biology at the University of Colorado School of Medicine. Sandy served as a meeting blogger for Experimental Biology 2019.

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